One of the tasks in finish carpentry involves the trimming of doors and windows with mitered casements. It is desirable to make the miter joints with a close-fitting or “tight” fit, as this is indicative of high-quality workmanship. Miter saw tables have been developed for the purpose of sawing the casements to form the miter joints. A typical miter saw table comprises a central table to which a pivot arm of the saw is rotatably mounted on a vertical axis. A fixed fence comprising coextensive lateral wings extend from each side of the central table, the rear edges of the wings having vertical rail elements and against which a work piece to be cut is maintained during the cutting operation.
Difficulty is often encountered in making tight mitered joints with current methods. This is primarily due to wood movement and fastening methods. Limitations of spring-loaded detents in the angular adjustment features of the pivot arms of miter saws and the small increments on the miter scales make it difficult to make the slight adjustments necessary to make fine adjustments in the cuts. Even when the detents and protractor scale of the miter saw are nearly perfect and produce cut angles that are perfectly divided, slight changes in humidity regularly open up what was once a well-fit miter joint when initially installed.
Numerous methods and tools have been devised in an attempt to improve the mitered casement, including the use of iron clamps, spring clamps, band clamps and other corner clamping devices, along with dowels and splines. Some carpenters use screws to hold a mitered joint together. However, because of the tapering thicknesses of most casements it is difficult to keep the screws from breaking through the surface of the casement. It is also difficult to position the screw so as to maintain generally constant pressure along the length and width of the miter joint. In addition to these shortcomings, current tools and methods are also time-consuming. There is a need to fabricate close-fitting miter joints in a speedier way. There is a further need for miter joints having greater permanence.